Self-regulating skimming weir apparatus having a constant discharge at any desired setting



Se t. 30, 1969 s. F. GRIGGS 3,469,404

SELF-REGULATING SKIMMING WEIR APPARATUS HAVING A CONSTANT DISCHARGE AT ANY DESIRED SETTING Filed April 22, 1968 4 Sheets-Sheet 1 I NVEN TOR. 5AM GE/GGS Sept. 30. 1969 s. F. amass 3,469,404

SELF-REGULATING SKIMMING WEIR APPARATUS HAVING A CONSTANT DISCHARGE AT ANY DESIRED SETTING Filed April 22, 1968 4 Sheets-Sheet 2 INVENTOR. $4M GE/GGS 4 7' TOE/V575.

Sept. 30, 1969 s. F. amass 3,469,404

SELF-REGULATING SKIMMING WEIR APPARATUS HAVING A CONSTANT DISCHARGE AT ANY DESIRED SETTING Filed April 22, 1968 4 Sheets-Sheet 3 INVENTOR 54M 5 619/665 ATTOE/VEKS'.

I Sept. 30, 1969 s. F. GRIGGS SELF-REGULATING SKIMMING WEIR APPARATUS HAVING A CONSTANT DISCHARGE AT ANY DESIRED SETTING Filed April 22, 1968 4 Sheets-Sheet 4.

INVENTOR. 51444 E GP/GGS BY My M United States Patent SELF-REGULATIN G SKHVIMDJG WEIR APPARATUS HAVING A CONSTANT DISCHARGE AT ANY DE- SIRED SETTING Sam F. Griggs, 160 N. Webster St., Independence, Calif. 93526 Filed Apr. 22, 1968, Ser. No. 723,079 Int. Cl. E021) 7/40 US. Cl. 61-23 31 Claims ABSTRACT OF THE DISCLOSURE A skimming weir apparatus comprising a pivoted water chute the intake end of which is a rounded-rested weir so constructed that the characteristics of the crest, the throat and the nappe remain constant regardless of the stage (depth) of the water. Cam, push-rod and compensator means are provided to maintain the head of water constant despite very substantial variations in the stage. Because of the stated factors, the discharge remains constant at any setting. A ballast system is employed to permit selection of various discharge rates, and gauge means are pro vided to indicate the discharge rate.

Background of the invention Field of the invention-The invention relates to the field of weirs or water-discharge devices which are adapted to maintain a predetermined rate of discharge from a body of water, regardless of variations in the stage or depth of the water in such body.

Description of the prior art.-For many decades, various patentees have attempted to provide a practical, accurate and rugged means for achieving a constant rate of water discharge despite variations in the stage (depth of) the water in a reservoir, irrigation ditch, etc. Such priorart attempts to solve the problem were unsuccessful for various reasons, including inaccuracy, instability, insensitivity, clogging of the intake by debris, damage to the weir crest, inability to operate successfully at low stages, inaccessibility of the float and ballast elements, difficulty of effecting ballasting and gauging, high cost, lack of ruggedness, susceptibility to icing, etc.

Representative patents in the field of constant-discharge devices include Patent 832,495 for a Reservoir Gate, Patent 1,108,090 for a Constant-Discharge Irrigation- Module, and Patent 2,079,063 for a Liquid Flow Control. A patent in a different field, that of fuel controls, is Patent 2,178,477 for a Fuel Control Device or the Like.

Summary of the invention In accordance with the present invention, the intake end of the pivotally-mounted discharge chute is constructed as a rounded-crested weir, being a section of a surface of revolution the axis of which is perpendicular to the plane of pivotal movement of the chute. Accordingly, the characteristics of the crest of the weir do not change despite substantial variations of the angle of the chute. The shape of the throat, and the characeristics of the nappe, are also maintained substantially constant. Very importantly, debris does not catch or pile up on the crest of the weir, nor is such crest subject to deterioration or damage. A combination push-rod and cam mechanism is provided to maintain the uppermost region of the weir crest at the same elevation relative to supporting floats therefor, and compensator means are provided to compensate for the complex effects of changes in buoyancy and changes of the weight of the water in the chute. Because the uppermost region of the crest remains at the same elevation relative to the floats, gauge means may be provided on the floats to record the head of Water passing over the weir crest. An

3,469,404 Patented Sept. 30, 1969 Brief description of the drawings FIGURE 1 is a perspective view showing the portions of the self-regulating skimming weir apparatus which appear above the surface of a body of water;

FIGURE 2 is a top plan view of the apparatus;

FIGURE 3 is a vertical sectional view on line 3-3 of FIGURE 2 and showing the chute in several pivoted positions;

FIGURE 4 is a transverse sectional view taken on line 44 of FIGURE 3;

FIGURE 5 is an isometric view illustrating the throat and crest portions of the weir;

FIGURE 6 is a longitudinal sectional view illustrating one of the floats;

FIGURE 7 is a view, showing the chute in section and the floats in end elevation, of an embodiment wherein an automatic head-recorder apparatus is provided; and

FIGURE 8 is a schematic view illustrating the operation push-rod and cam means for maintaining the uppermost region of the weir crest at a constant elevation relative to the float means.

Description of the preferred embodiment Throughout this specification and claims, reference to water denotes any liquid. The stage is the depth of water in the reservoir, ditch, pond or other body of water from which liquid is discharged. The nappe is the sheet of water which overflows the crest of the weir. The head is the depth of water passing over the uppermost region of the crest of the weir, that is to say, the vertical dimension of the nappe. The throat is the approach channel immediately upstream from the uppermost region of the crest.

Although the present weir apparatus may be employed in substantially any body of water, including relatively shallow ditches, it is illustrated in the drawings as located in a reservoir which is defined in part by a concrete brestwall 10 having a discharge opening 11 (FIGURE 3) therethrough. An inclined bulkhead 12, having triangular side walls, is sealingly connected to horizontal and vertical portions of brestwall 10. The bulkhead has a rectangular opening 13 therethrough for reception of a swing joint 14. Suitable sealing means, such as the felt gasket 15, is mounted on bulkhead 12 around opening 13 and rubs against swing joint 14 in order to prevent leakage of water.

The swing joint 14 is a hollow cylinder having closed ends. The swing-joint portion adjacent opening 11 is provided with a large opening in order that discharging water may pass to and through opening 11.

An elongated water chute 16 is fixedly and sealingly connected to swing joint 14 and extends for a considerable distance from bulkhead 12. Chute 16 is preferably rectangular in cross-sectional shape, and increases progressively in size in a direction away from the bulkhead. The chute is closed throughout the majority of its length by a cover portion 17 adapated to prevent ingress of water except through the intake means described below. The cover or wall portion 17 is preferably planar, as is the chute bottom wall 16a disposed therebeneath. The planes of both walls 16a and 17 contain lines which are parallel to the pivot axis of the chute.

The hollow cylindrical swing joint 14 is pivotally or rotatably connected to bulikhead 12 by means of a pivot or axle shaft 18. Such shaft extends through the centers of the disc-shaped end walls of swing joint 14, and also (in sealed relationship) through the triangular side walls of bulkhead 12. Suitable cap means (FIGURE 2) are provided to prevent axial shifting of the shaft 18.

The pivot or axle shaft 18 is horizontal and permits upward and downward pivotal movement of chute 16 through a relatively wide angle, for example 30 degrees or greater if desired. The chute pivots in a vertical plane which is perpendicular to the pivot shaft.

THE CONSTANT-SHAPE, ROUNDED-CRESTED PIVOTED WEIR It is a major feature of the present invention that the characteristics of the rounded crest of the weir, and of the throat, remain constant despite the fact that the chute 16 pivots upwardly and downwardly to assume various inclinations. In this connection, it is strongly emphasized that the weir should have a rounded crest since sharpcrested weirs, particularly when used over long periods of time, are extremely difficult to maintain. This is because the crest of a sharp-crested weir is likely to become dulled or rusted, or it may be damaged by floating debris and ice. Furthermore, sharp-crested weirs are readily clogged by floating debris, especially at low heads.

Not only are sharp-crested weirs difficult to maintain, and readily clogged, but they are subject to other serious disadvantages. One such disadvantage is that the nappe of a sharp-crested weir is not free from modification in form when the head is low. Another disadvantage is the aeration means must be provided below a sharp-crested weir. This is to prevent exhausting of air beneath the nappe, causing a reduction of pressure with corresponding change in discharge for a given head.

It is extremely important that the shape of the weir remain constant, regardless of the pivoted position of the chute, because the amount of water which will pass over a rounded-crested weir depends to a large extent upon the shape of its crest and of its throat. In accordance with one major aspect of the present invention, the inlet means to chute 16 is a rounded-crested weir the crest Wall 20 of which is a substantial portion of a surface of revolution. The axis (center) of the surface of revolution is horizontal, being parallel to axle shaft 18, such axis being indicated at 21 in the lower-left portion of FIGURE 8. Preferably, the surface of revolution is a cylinder, as illustrated in the drawings.

Referring to FIGURE 3, it will be seen that the described configuration of crest wall 20 causes the shape of the Weir crest to remain constant whether the chute 16 is in the lower position illustrated in solid lines, or in the upper position shown in phantom lines. In either case, the water flows over a crest which is cylindrical about the center 21 (FIGURE 8), and between side walls as will be described subsequently.

The constant crest shape occurs despite the fact that the location of the uppermost region of the Weir crest, and which will hereinafter be referred to as the line of tangency (the line of tangency between a horizontal plane and the convex upper surface of crest wall 20), changes substantially (and progressively) along the length of crest Wall 20. Thus, the line of tangency is indicated at 22 relative to the solid-line low-stage showing of FIG- URE 3, and at 23 relative to the phantom-line high-stage showing of such figure. Such lines of tangency 22 and 23 are also indicated in FIGURE 8, it being understood that in each instance the lines extend perpendicular to the planes in which FIGURES 3 and 8 are drawn.

As illustrated in FIGURES 3 and 8, the plane of chute bottom wall 16a is a substantial distance below the uppermost portion of cylindrical crest wall 20, such distance being sufiicient to insure that the nappe will maintain the proper form even when Wall 16a is relatively horizontal as occurs when the stage is low. The discharge rate will then remain constant, and at a high lever as desired, even at low stages.

From the region of merger with chute bottom wall 16a, crest wall 20 extends arcuately about axis or center 21 (FIGURE 8) through a substantial angle which depends in part upon the desired amount of pivotal movement of chute 16. In the illustrated form, wherein the desired pivotal movement of chute 16 is on the order of 30 degrees (although a greater pivotal movement is possible), the crest wall 20 extends about center 21 through an angle of approximately degrees. Crest wall 20 merges with bottom wall 16a through a smoothly-curving concave merger region which is tangential to both walls 20 and 16a.

Although the cover portion 17 of the chute 16 terminates at a region generally above line of tangency 22 (there being an angle bar 24 provided to stiffen the cover edge), the side Walls extend in an upstream direction for a considerable distance from crest wall 20. The extensions of the chute sides are indicated at 26, and should be parallel to each other and perpendicular to the axle shaft 18 and to the central axis 21 of crest Wall 20. Such side wall extensions 26 aid in defining the throat of the Weir, and (like crest wall 20) remain constant regardless of the pivoted position of chute 16.

The parallel side wall extensions 26 which are upstream from the crest wall 20 provide the beneficial etfect of making sure that the water flowing toward the crest wall is laminar and parallel, and engages such wall 20 in a flow direction perpendicular to the line of tangency. Thus, the flow direction is generally in the plane of vertical pivotal movement of the chute 16. Another advantage produced by the forward extensions 26 is that they insure that any extremely large floating objects will be maintained a substantial distance away from the crest wall 20 and therefore will not seriously affect the flow over such wall.

Although the side wall extensions 26 are parallel, the water approaching the line of tangency increases in velocity due to the progressively reducing depth caused by the upward curvature of crest wall 20. Stated otherwise, the upper surface of crest wall 20 is convex, so that the depth of Water thereover progressively reduces as the line of tangency is approached. Such increase in velocity produces the beneficial effect of aiding debris to pass over the weir crest. It also produces the effect that the flow of water over the weir crest is maximized, even when the stage is low.

In summary, therefore, the crest form and throat form remain constant despite pivoting of the chute. In addition, the form of the nappe remains substantially constant. There is no need for aeration since the weir is not sharp crested. Accordingly, and because the head remains the same (at any setting) as described below, the rate of discharge is constant.

The crest and throat shapes are such that critical depth is caused to occur regardless of the pivoted position of the chute. This is an important feature for various reasons, as set forth in the Handbook of Hydraulics, fifth edition, by King and Brater, published by McGraw- Hill Book Company, at Section 83 and following.

The present weir intake (inlet means) does not need a stilling basin, and does not require calibration. The flow is constant, at a high rate, and the metering operation is sensitive. The installation is low profile, and permits a high degree of submergence, although it is pointed out that the present intake does not operate as a fully submerged or drowned weir.

THE PUSH-RODS AND ASSOCIATED CAM AND FLOAT MEANS Floats 27 and 28 are provided on opposite sides of the portions of chute 16 (and crest wall 20) which are remote from bulkhead 12. The detailed construction of such floats is stated hereinafter, on conjunction with the description of a ballasting system. Such floats are connected to each other by means of an angle iron 29 (which is secured to the upper float portions remote from bulkhead 12) and also by means of a cam-follower rod 31.

As best shown in FIGURE 4, the cam-follower rod 31 is a cylindrical member which extends through bushings 32 in the floats 27 and 28. Since the cam-follower rod 31 fits in bushings 32 which are fixedly secured to floats 27 and 28, as (for example) by welding, it follows that the position of the rod 31 is fixed relative to the floats. However, the portion of cam-follower rod 31 which is between the floats is not fixed relative to chute 16, but instead is movably positioned below the cylindrical crest wall 20. More specifically, cam-follower rod 31 extends below the abovedefined lines of tangency 22 and 23 (FIGURES 3 and 8) as well as below other and unshown lines of tangency which occur when the chute is at pivoted positions between those illustrated.

The central portion of cam-follower rod 31 is constrained to remain in contact with (or closely adjacent) the concave lower surface of cylindrical crest wall 20. This is accomplished by means of generally U-shaped cam elements 33 which are suitably welded or otherwise secured to opposite sides of the weir as best shown in FIG- URE 5. Elements 33 have upwardly extending end portions 33a which are welded to the weir or chute, and central portions 33b which are arcuate about the above-defined central axis 21 of crest wall 20. Thus, the portions 33b are parallel to crest wall 20 and serve to confine the cam-follower rod 31 as desired.

The ends of cam-follower rod 31 are suitably connected to push-rods 34 and 35 which are pivotally connected to opposite side walls of bulkhead 12. The pivotal connections to the bulkhead 12 may be of any suitable type, and are indicated at 36. As shown in FIGURE 2, the pivotal connections 36 may comprise stub shafts which extend outwardly from the side walls of the bulkhead, such stub shafts having rotatable collars thereon which are secured to the push-rods 34 and 35.

The axis of pivotal movement which extends through the line of tangency 22-23 (and adjacent other and unmember 18 and spaced therefrom, being thereabove and somewhat to the right as viewed in FIGURE 3. The locations of axle 18 and pivot connections 36, and the lengths of push-rods 34 and 35, are so selected that camfollower rod 31 will remain (as stated above) adjacent the line of tangency 22-23 (and adjacent other and unshown lines of tangency therebetween) regardless of the inclination of the chute 16. Thus, when the chute is in the low position shown in solid lines in FIGURE 3, the camfollower rod 31 is in the ends of U-shaped cam elements 33 which are relatively adjacent the bulkhead 12. After upward pivotal movement of the chute to the position shown in phantom lines in FIGURE 3, the cam-follower rod 31 has moved to a location relatively adjacent the portions of elements 33 which are remote from the bulkhead.

The operation of the push-rods 3435 and associated cam and float elements may best be understood by reference to FIGURE 8, which illustrates what would occur if rod 31 were connected fixedly to the chute instead of by the described cam means. In order for such a fixed connection to occur without looking the chute against pivotal movement, the push-rods 3435 would be pivotally connected to the bulkhead 12 at an axis coincident with axle 18 (instead of at the pivot connections 36). Thus, the pivotal movement would have a radius R centered at axle 18. If the connections to the chute were such as to locate rod 31 adjacent line of tangency 22 shown at the lower-left portion of FIGURE 8, upward pivotal movement would cause the element 31 to be at 31a (instead of at 31, upper-left portion of FIGURE 8, which is where the cam-follower rod is actually located in accordance with the present cam operation). Such a location at 31:: would cause the line of tangency to be at 31th, which the line of tangency always remains at the same eletangency 23.

It will thus be seen that, all other factors being equal, upward movement of the chute would (in the absence of the present cam means) cause the line of tangency to rise relative to the floats, which would then decrease the head of water above the line of tangency and thus reduce the rate of discharge down the chute. Such action is prevented by the described cam means since the line of tangency always remains at the same elevation relative to the floats. It follows that the compensating means, described subsequently, need not compensate for changes in the line of tangency relative to the floats, and it also follows that the gauge elements (also described subsequently) may be mounted on the floats and provide accurate read ings in a practical, simple and linear manner.

Despite the fact that the cam-follower rod 31 is movable relative to chute 16, the described apparatus is extremely stable and is not subject to malfunction due to wind, wave action, etc. The floats 27 and 28 are fully constrained by the push-rods 34 and 35 since such rods connect to the end portions of rod 31 (FIGURE 4), and such rod 31 extends through bushings or sleeves 32. It is therefore impossible for the floats to cant, wobble, etc. Similarly, the chute 16 is fully constrained by its pivot axle 18 and by the crest wall 20 and associated cam elements 33 which define the path of movement of camfollower rod 31. The cam action is such that the floats move longitudinally relative to the chute.

The positioning of cam-follower rod 31 in floats 27 and 28 is such that the weir is not of the submerged type. Such cam-follower rod 31 is horizontal, parallel to the axis 21 (FIGURE 8) of crest wall 20, parallel to the pivot axis 18 of the chute 16, and perpendicular to the plane of pivotal movement of the chute.

It is pointed out that the present floats are only partly submerged. They are therefore stable and sensitive in operation, and are to be distinguished from fully-submerged floats which tend to act in a sluggish and waterlogged manner.

In summary, therefore, the present invention achieves a pivotally-mounted rounded-crested weir which is sensitive and fully stable in operation, and which has a constant-elevation line of tangency (relative to the floats) despite movement of the chute to different inclined positions.

COMPENSATOR APPARATUS Because of the previously-indicated construction by which the line of tangency always remains at the same elevation relative to the floats, the compensator apparatus need only compensate for two variables. The first variable is the change in the weight of the water in chute 16. When chute 16 is relatively horizontal, as shown in solid lines in FIGURE 3, water flows slowly and accordingly (to achieve a given flow rate) must be relatively deep and therefore heavy. On the other hand, when the chute is in an elevated position such as is shown in phantom lines in FIGURE 3, the water in the chute (at the above-indicated given flow rate) is flowing much faster and is therefore more shallow and less heavy.

The second variable compensated for by compensator means is the change in buoyancy of the chute as it pivots upwardly and downwardly. When the chute is in the low or solid-line position of FIGURE 3, only a relatively small proportion of the chute is below the surface of the water, which means that the buoyancy forces acting upon the chute are relatively small. Conversely, when the chute is in the upper or phantom-line position, a very large proportion of the chute is below the surface of the water, so that the buoyancy forces are much greater.

The two described variables or factors, namely the change in weight of water in the chute, and the change of the buoyancy forces acting on the chute, are similar in that both require the addition of compensating weight to the chute in response to upward pivotal movement thereof. The necessary compensating weight forces are complex in nature.

In accordance with the present invention, a highly simple, economical and practical compensator means is provided in a readily accessible location, and at such location that it need not be submerged under water and is therefore not subject to corrosion, icing, fouling, etc. Although the compensating means is simple and practical, it generates the necessary complex compensating weight forces. Such means comprises a weight 41 which is adjustably mounted on a moment frame or arm 42, the latter being pivotally associated at one end with a fixed support and movably associated at the other end with the chute 16.

More specifically, weight 41 is illustrated to be a cylindrical mass of metal (or other heavy substance) having skid or slide elements at opposite ends thereof. Such skid or slide elements rest slidably upon the moment frame 42, which is illustrated (FIGURE 1) to comprise an elongated rectangular frame formed of angle bars. A threaded adjustment shaft 43 is pivotally connected to weight 41, and extends freely through the frame bar which is remote from the chute. A nut 44 (FIGURE 3) having a crank arm connected thereto is threaded on shaft 43 and adapted upon rotation by the crank to shift the position of shaft 43 and thus the position of the weight 41.

Frame 42 is pivotally connected at 46 to brackets 47 which are suitably secured to the upper portion of breastwall 10. Adjustable threaded stop-shafts 48 are threaded through nuts 49 on brackets 47, so that rotation of the shafts 48 by cranks 50 will adjust the positions of stop elements 51. Such stop elements 51 are positioned to be engaged by the opposite sides of rectangular moment frame 42 and thus limit the degree of downward pivotal movement thereof.

A yoke 52 is mounted fixedly on the end of moment frame 42 remote from pivot connections 46, having rotatably mounted therein a wheel 53 adapted to move along a track element 54. Track 54 is mounted on the upper or cover portion 17 of chute 16, lying in the plane of vertical pivotal movement of the chute.

In the operation of the compensator means, the magnitude of the weight 41 is determined at the factory in an empirical manner, and varies considerably with factors including the width of the chute 16. Thus, for example, if the weir is of a high-flow type wherein it is desired that the spacing between opposed side wall extensions 26 be great, then the size of the weight 41 is also made relatively great.

The setting of the adjustment shaft 43 (that is to say, the positioning of the weight 41 on frame 42), and the settings of stop-shafts 48, are determined in accordance with an empirical table supplied by the manufacturer and which is related to the head of water passing over the line of tangency. Thus, when the head is changed through operation of the ballasting system described below, the setting (positioning) of the weight 41 (and, in some cases, of stop-shafts 48) is also changed.

When the chute 16 is in the lower position shown in solid lines in FIGURE 3, the wheel 53 engages the track 54 at a region relatively adjacent axle shaft 18. It follows that the moment arm is relatively short. On the other hand, when the chute 16 is in an upper position as shown in phantom lines, the moment arm is much greater. In addition, it is to be noted that when the chute is in the upper position, a relatively small proportion of the weight is borne by the pivotal connections 46 to brackets 47, and a relatively large proportion of the weight is borne by the wheel 53 acting on its track 54 and thus on the chute. Conversely, when the chute is in the lower position, a much greater proportion of the weight is borne by the pivotal connections 46 to fixed brackets 47.

It follows that for any setting of the weight 41 on its frame 42, the effective force exerted downwardly against chute 16 will increase as the chute pivots upwardly. The location of the axis of pivots 46, the location of the region of engagement with the chute 16, and other factors, are caused to be such that this increase in the effective down- Wardly force exerted by the compensator means counterbalances the two above-described complex forces. Accordingly, the head of water remains substantially constant over the entire range of pivotal movement of the chute. Such constancy is achieved without adjusting the position of weight 41, except when it is desired to change the flow.

To change the head of water flowing over the weir crest, and thus the rate of flow, it is merely necessary to 8 rotate the nut 44 (FIGURE 3) in order to change the location of weight 41 in accordance with tables supplied by the manufacturer. Thereafter, the ballast system is operated to change the elevation of floats 27 and 28 in the Water, as next described.

THE ADJUSTABLE BALLAST SYSTEM Each of the two floats 27 and 28 is sufiiciently large to maintain the chute 16 at an elevation sufiiciently high to prevent submerging of the weir. In accordance with the present ballasting system, each float is a hollow member formed, for example, of sheet metal. The above-indicated bushings 32 pass through the transverse medial planes of the respective floats, and preferably substantially beneath the centers of the floats, in order to enhance the stability of the system.

Float 27 will be described in detail relative to FIGURE 6 and the other figures, it being understood that the remaining float 28 is identical thereto. Float 27 is an elongated rectangular member having inclined end surface portions 56 which are preferably at an angle of approximately 60 degrees from the horizontal. Such inclined ends 56 enhance the stability of the floats, and aid in maintaining the same level despite operation of the ballasting means.

Bulkheads 57 are provided at the end portions of the floats, relatively adjacent the lower portions of surfaces 56, and define water-tight float compartments 58. Such compartments have the same size and shape, and are spaced the same distance from the bushing 32, so that they create equal torques insuring that neither end of the float will be at an elevation substantially different from that of the other end thereof.

The space within the floats and between the bulkheads 57 comprises a ballast chamber which is divided or subdivided into a plurality of sub-chambers 59. Thus, two vertical baflles 61 are provided and are formed with suitable holes or openings 62 and 62a which permit restricted communication between the sub-chambers while preventing excessive sloshing of water therein.

Referring particularly to FIGURE 4, an inlet valve 63 is provided at the lower region of float 28 and operates, when open, to admit water from the reservoir into the ballast chambers 59. For this purpose, a valve-control rod 64 and associated handwheel 65 are provided. The Water thus admitted will also flow into the remaining float 27, since such floats are interconnected by means of a pipe 66 extending between the lower portions thereof.

A pneumatic system comprising pipes 67 and 68 is connected to the ballast chambers 59 at the upper portions of the float, having associated therewith a suitable manually-controlled vent valve 69 and also an air-inlet valve 70. Desirably, air-inlet valve 70 is a tire valve stem adapted to have associated therewith a suitable hand-operated bicycle or tire pump in order to permit pressurizing of the ballast chamber despite the absence of electrical power at the weir site. Alternatively, a suitable storage tank of compressed air maybe provided.

The remaining component of the float assembly comprises a keel 71 which is mounted between the floats 27 and 28 adjacent the lower portions thereof. The keel is disposed in the same medial plane as are bushings 32. Preferably, the keel 71 is mounted above the pipe 66 which connects the two ballast chambers. The keel further insures that the floats will remain level, and, furthermore, causes the floats to initially float sufficiently low in the water that ballast water will flow into the ballast chambers or sub-chambers 59 at a relatively rapid rate.

In the operation of the float and ballast system, and assuming that there is initially no water in the ballast chambers 59, the vent 69 is first opened, following which the handwheel 65 is turned to rotate shaft 64 and open the valve 63 to thereby admit water into the lower portion of float 28 and thus, through interconnecting pipe 66, into the lower portion of float 27. As the water flows in, the

floats 27 and 28 progressively sink lower into the water, causing lowering of cam-follower rod 31 and the associated crest wall 20. The head of water flowing over the weir is thus increased to increase the rate of discharge.

After the floats sink to the desired depth, and which is determined by gauge means described below, valve 63 is closed to prevent further inflow of water.

When it is desired to elevate the floats and thus decrease the head of water flowing over the weir crest 20, it is merely necessary to close the vent 69 and then apply a suitable air-pressure source to air-inlet valve 70 and thereby pressurize the portions of chambers 59 above the water levels therein. Thereupon, and despite the fact that the applied air pressure need only be very small, opening of valve 63 will result in outflow of water from both floats whereby to effect elevation of the floats and crest wall 20 as desired. Valve 63 is then re-closed.

Tables supplied by the manufacturer indicate to the user of the weir that when the head is a certain number of inches, the rate of water discharge will be a specified number of cubic feet per second. Thus, it is merely necessary for the user to operate the air pressure and valve means until the head is as desired. Also, and as stated above, the tables indicate to the user the setting of the compensator weight 41 which is appropriate for any particular head.

THE GAUGE MEANS Because the line of tangency 2223 is always at the same elevation relative to floats 27 and 28, a simple vertical staff gauge 76 may be mounted on float 28 (or on float 27) as by a bracket 77. The lower end of the staff gauge 76 represents the zero point and is caused to be at the same elevation as the line of tangency 22-23. The gauge is then read by merely noting .where the surface of the water in the reservoir contacts the indicia on the gauge. Since the zero point on the gauge represents the lower surface of the nappe (that surface in contact with the line of tangency), the gauge accurately indicates the head of water flowing over the weir.

Referring next to FIGUREj7, which illustrates a second embodiment of the invention, a continuous-record head recorder may be provided in addition to or in place of the staff gauge. The illustrated continuous recorder comprises a cylindrical tank 78 which is mounted on float 27, such tank having a conical bottom portion 79 the apex region of which is open in order to form a port permitting flow of water into and out of the tank. The tank defines a float well in which is mounted a suitable float 81 connected by a cable 82 to a conventional float-operated clock-driven water stage recorder 83. The cable 82 passes over pulleys indicated at 84 and 85. Bracket means 87 are provided on the floats in order to support the float tank 78 and also the stage recorder. The recorder 83 is caused to be sufliciently far off center to compensate for the weight of the tank78 and thus insure against listing of the float apparatus.

The recorder 83 and tank 78 are located in substantially the same medial plane as are keel 71 and bushings 32, such plane containing the cam-follower rod 31. This prevents tilting of the float apparatus.

The foregoing detailed description is to be clearly understood as given by way of illustration and example only, the spirit and scope of this invention being limited solely by the appended claims.

I claim:

1. A skimming weir apparatus adapted to deliver a predetermined output despite substantial variations in the water stage, which comprises: i

an inclined chute adapted to transmit water to a desired region,

means to change the inclination of said chute in response to changes in the stage of the body of water which supplies said chute, and,

inlet means connected to the upper end of said chute and movable therewith for reception of water from said body and for delivery of such water to said chute,

said inlet means comprising a rounded-crested weir the shape of which remains substantially constant despite substantial changes in the inclination of said chute.

2. The invention as claimed in claim 1, in which said inlet means further comprises side wall means extending upstream from the crest of said weir to cause water to flow toward said crest in a direction perpendicular thereto, said side wall means being so shaped that the throat of said weir maintains a substantially constant shape despite substantial changes in the inclination of said chute.

3. The invention as claimed in claim 1, in which said chute pivots in a vertical plane about a generally horizontal pivot axis, and in which the upper surface of said weir is a substantial section of a surface of revolution about an axis parallel to said pivot axis, the upper surface of said section being convex.

4. The invention as claimed in claim 3, in which surface of revolution is a cylinder.

5. The invention as claimed in claim 4, in which the bottom wall of said chute, in at least the region thereof which is adjacent said weir, lies in an inclined plane which intersects said cylinder section below the uppermost region thereof.

'6. The invention as claimed in claim 5, in which said chute Wall and said cylinder section are connected by a wall portion which is generally tangential to both said chute wall and said cylinder section.

7. A skimming weir apparatus for effecting a predetermined rate of discharge from a body of water despite changes in the stage of such body, which compirses:

float means,

an inclined water chute the lower end of which is adapted to discharge water from said body,

means to pivotally connect the lower portion of said chute to a fixed support to thereby permit pivotal movement of said chute in a vertical plane,

inlet means provided at the upper end of said chute to admit water thereto from said body, said inlet means including a rounded-crested weir,

and

means to connect the upper portion of said chute to said float means whereby to pivot said chute in response to the stage of the water in said body,

said last-named means including means to effect relative movement between said inlet means and said float means in response to pivotal movement of said chute, and in such manner that the elevation of the uppermost region of the crest of said weir remains constant relative to the elevation of said float means.

8. The invention as claimed in claim 7, in which the upper surface of said weir is convex and is a substantial section of a surface of revolution about an axis parallel to the axis of said pivotal-connector means.

9. The invention as claimed in claim 7, in which said means to effect said relative movement includes a cam mechanism.

10. The invention as claimed in claim 7, in which said rounded-crested weir is formed by an element which is a substantial portion of a figure of revolution the axis of which is perpendicular to said plane, the upper surface of said weir element being convex and the lower surface of said weir element being concave, in which a camfollower rod is mounted perpendicular to said plane and adjacent said lower surface of said weir element, in which said cam-follower rod is connected with said float means, and in which push-rods are connected to said cam-follower rod and are pivotally connected to said fixed support for pivotal movement about an axis perpendicular to said plane, said last-mentioned axis being spaced a substantial distance from the axis of said pivotal-connector means for said chute.

11. The invention as claimed in claim 10, in which said figure of revolution is a cylinder.

12. The invention as claimed in claim 10, in which said axes and said elements are so related that said cam-follower rod is positioned at all times directly beneath the uppermost region of the crest of said weir element.

13. The invention as claimed in claim 10, in which said float means comprises first and second corresponding floats disposed on opposite sides of said chute, said floats being only partially submerged, and in which said camfollower rod extends through said floats in such manner that the vertical and horizontal positions of said rod are fixed relative to said floats.

14. The invention as claimed in claim 7, in which gauge means are mounted on said float means and adapted to measure the head of the water above said uppermost region of said weir crest.

15. A self-regulating skimming weir apparatus, which comprises:

an inclined water chute adapted to discharge water from a body thereof,

means to pivotally mount said chute to a support for pivotal movement about a horizontal axis,

float means to pivot said chute to different inclined positions in response to changes in the stage of said body of water supplying said chute,

inlet means to admit water into the upper end of said chute for discharge therethrough, and

compensator means to compensate for variations in the weight of the water in said chute, and also for variations in the buoyant forces acting upon said chute, as said chute pivots to different inclined positions,

said compensator means comprising an inclined moment arm having one end pivotally connected to a support for pivotal movement of said moment arm about a horizontal axis spaced a substantial distance from, and parallel to, said axis of said chute,

said moment arm also having another end adapted to move to various positions along said chute in response to pivoting of said chute, said compensator means further comprising weight means provided on said moment arm for application of downward force to said chute.

16. The invention as claimed in claim 15, in which means are provided to adjust said weight means to different longitudinal positions along said moment arm, thereby varying the amount of said downward force.

17. The invention as claimed in claim 15, in which said other end of said moment arm is provided with a wheel which rides along an upper surface of said chute.

18. The invention as claimed in claim 15, in which the pivot axis of said moment arm is located generally above the pivot axis of said chute.

19. The invention as claimed in claim 15, in which adjustable stop means are provided on a support and are adapted to limit the downward pivotal movement of said moment arm.

20. The invention as claimed in claim 15, in which the locations of said pivot axes, and the inclinations of said chute and of said moment arm, are such that said other end of said moment arm moves progressively away from said axis of said chute in response to upward pivotal movement of said chute.

21. The invention as claimed in claim 15, in which said pivot axis of said moment arm is disposed far above said pivot axis of said chute, in which said other end of said moment arm rides along the upper surface of said chute, in which said other end of said moment arm is disposed at a lower elevation than is said one end thereof, and in which said other end of said moment arm moves progressively away from said pivot axis of said chute in response to upward pivotal movement of said chute.

22. The invention as claimed in claim 21, in which said chute has a cover which supports said other end of said moment arm, and in which said other end is always above the surface of said body of water supplying said chute.

23. An adjustable skimming weir for producing a constant discharge at any adjusted position, which comprises: conduit means to discharge water from a body thereof, said conduit means having intake means at the upper end thereof for reception of water from said body,

float means to support said intake means at such an elevation relative to the surface of said body of water that a predetermined head of water flows into said intake means and thus into said conduit means,

said float means having a ballast chamber therein, and

means to introduce water into said ballast chamber and to discharge such water therefrom, whereby to regulate the water line of said float means and thus vary said predetermined head of water.

24. The invention as claimed in claim 23, in which said last-named means comprises valve and conduit means adapted to controllably admit water from said body into said ballast chamber, means to introduce pressurized air into said ballast chamber, and valve-controlled means to vent said ballast chamber.

25. The invention as claimed in claim 23, in which gauge means are provided on said float means to indicate the depth thereof in said body of water.

26. The invention as claimed in claim 23, in which said conduit means is a pivotal chute, in which said float means comprises first and second corresponding elongated hollow floats connected to said chute and disposed on opposite sides thereof and generally parallel to the plane of pivotal movement thereof, and in which conduit means are provided to effect communication between ballast chambers in said floats.

27. The invention as claimed in claim 26, in which an air-filled floatation chamber is provided in each end of each of said floats, in which ported baffle means are provided to prevent excessive movement of water in said floats, and in which the lower face portions of the float ends are inclined.

28. The invention as claimed in claim 26, in which keel means is mounted on the lower portions of said floats.

29. An adjustable, self-regulating skimming weir for discharging a constant volume of water from a body of water despite changes in the stage, which comprises:

an elongated chute adapted to discharge water from said body,

means to pivotally connect the lower end of said chute to a support for pivotal movement of said chute in a vertical plane, inlet means provided at the upper end of said chute and comprising a rounded-crested weir which is so shaped that the crest and throat thereof remain substantially constant despite said pivoting of said chute, float means provided adjacent said inlet means, means to connect the upper portion of said chute to said float means whereby to pivot said chute in response to the stage of the water in said body,

said last-named means including means to effect relative movement between said inlet means and said float means in response to pivotal movement of said chute and in such manner that the elevation of the uppermost region of the crest of said weir remains constant relative to the elevation of said float means, and compensator means to compensate for variations in the weight of the water in said chute, and also for variations in the buoyant forces acting upon said chute, said compensator means comprising an inclined moment arm having one end pivotally connected to a support,

said moment arm also having another end adapted to move progressively to various positions along said chute in response to pivoting said chute,

13 14 provided on said moment arm for application of References Cited downward force to said chute.

30. The invention as claimed in claim 29, in which gauge UNITED STATES PATENTS means are provided on said float means to ga ge the h 775,532 11/1904 Hart et al. 61-23 of water above said uppermost region of said weir crest. 332 495 10 90 n 1 3 31. The invention as claimed in claim 29, in which said 5 947,326 1/1910 Cauaway 61 23 float means have a ballast chamber therein, and in which 1 065 761 6/1913 Ziegler et a1 means are provided to introduce water into said ballast 1136'066 4/1915 Walker et 61 23 chamber and to discharge such water therefrom, whereby to regulate the water line of said float means and thus 10 PETER CAUN, Primary Examiner vary the head of water passing over said wen".

323 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,469, 404 Dated September 30, 1969 Inventor) Sam F. Griggs It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 12, line 75, before "said chute, Column 13, before line 1, insert the words said compensator means further comprising weight means the clause at the top of Column 13 should read as follows:

said compensator means further comprising weight means provided on said moment arm for application of downward force to said chute.

Thus,

SIGNED AND SEALED JUL? E70 (SEAL) Attest:

Edward M. Fletcher, Jr.

Attesting Officer wmxm E. 'SGHUYIJER, JR-

Commissioner of Patents insert of 

